Treatment of ores containing gold, silver, copper, nickel, and zinc.



U IT D STATES PA TENT OFFICE...

-Ilatented August 1905.

HENRY HlR SC-H-IN G, or, SAN-FRANCISCO, GALIFORNIA TREATMENT or catscommits cote, SILVER'ICOPPER, NICKEL, AND zmc.

srncmcsnon'formisg partof Letters Patent No. 735,512, dated August 4,903.

' v v Application filed March 19,1962. Serial No. 9d,964. (Nospecimens.)

To all whom it may concern:

. Be it" known that I, HENRY Hmsonme, a citizen of the United States,residing in.San

Francisco, in the county f,San Francisco and q ,5 State of California,have inventeda certain new and-useful Improvement inthe'Treatment ofOres Containing Gold, Silver, Cop? per, Nickel, and Zinc, of which thefollowing is alfull, clear, and exact description.

My invention relates to a process whereby the metals of complex andrefractory ores and tailings can be extracted, and more especially gold,silver, copper, nickel, and zinccan be produced separatelyandeconomical!-Theprocess is a continuous hydrometal urgical process, using as asolvent water, ammonia,

' and com ponndsthereof, and is carried on in' a simple apparatus, forwhich a separate application, Serial -NO .C85,320, has been filed.

2c The process is applicable directly to raw" comminuted ores andtail-ingscontaining the said metals if they are soluble-in mysolvent, orif they are refractory or not solublea preliminary treatment isrequired, consisting in 2 5 roasting,with or without salt, andmoistening with acidulated salt wateror salt solutions,-

' as explained below. The preliminary treat ment is to convert themetals and metal compounds in the ores or tailings into metal saltssoluble inwater, ammonia, and com pounds thereof, such as carbonate,sulfate, nitrate, and chlorid of ammonia. in many cases will notaccomplishing this, because by the application of heat one metal 5becomesa soluble salt and another under like conditions becomesindiflr'erent or insoluble.

For this reason no uniform and profitable extractionsconld be obtainedby means of the processes and apparatus hitherto employed.

49 It is my aim to provide a completeand perzinc no uniformconversion'is obtained of the metals or metalcom pounds into metal saltsRoasting v chemical distinction from the acid-dissolution version intosoluble salts.

soluble in water or ammonia and compound. thereof.- The reason of thisis'the complexity of the ore and the impossibility'to adapt 33 theroasting temperatu re equally to all metals and metal compounds in theore.- In order to remedy such defective roasted ore, I moisten it on thecooling-floor with salt solutions, such as ferric sulfate, ferricchlorid, or with a very dilute acid solution containing somesalt. V Suchsolutions I will call acidulatedsolution. Time must-be givenfor thereaction to. take place before subjecting the ore to the leachingprocess. By this reaction the reduced metals, and in the-case of copperthe formedcupricandcuprousoxids,as theycome from the roasting-furnaceare converted into saltssoluble in mysolvents. The conversion ofthe,cupric and'cuprous oxids into soluble hydrated cupri'c oxid'takes placeby the ac-- ,tion of the acid radical, which transforms one .molecule'into sulfate for chlorid, then under electrochemical act-ion dnc to thepresence of moisture dissociates itself therefrom, leaving solublehydrated cupric oxid, and then acting inthe same manner on thenextmolecule. The chemical formulae for this reaction if, for instance,H is used are as follows: l

1. ouo+H,so,=ou(H ).+So,. 3- SO +H Q=H SO,.- j f This illustrates that H80 is only the agency of the conversion, and therefore a very smallquantity only of the acid is required. Of course reasonable time isnecessary for a complete conversion of all the copper oxide in theore-body into soluble salts. It further illus trates the cheapness ofthe process and its 9o processes. i s v The use of acidulated solutionis recommended, above for ores in which the roasting process did notaccomplish a complete can- The cheapness of 5 the moistening processwill recommend itself for general application for all classes of oresand tailings, raw orroasted, with or without salt, in which there arecompounds that without. this moisteui ng process would remain insoluble.With this moistening process properly applied a uniform extraction ofthe metals present in the ore can he obtained by my sol-. .vent to apextent of ninety to ninety-five per cent. a result superior to anythingheretofore accomplished in any ammonia solvent, the reason for theprevious unsatisfactory results being the complexity of the ore bodiesas found in' nature and the consequent difficulty of transforming themetals uniformly into soluble salts by the methods heretofore in use. Myprocess is therefore a combination process, comprising a preliminarytreatment, followed by lixiviation, and is applicable and effective withores ortailings containing one, any or all of the metals-gold, silver,copper, nickel, and zinc. The extraction of the metals and theirconversion into commercial products will be explained farther on. a

I will now describe the process with ores or tailings containinggold,silver,copper,nickel,

metal compounds.

and zinc. \Vhen a chlorinating roast is carried out, there are formedamong othercompounds chloride of the preciousand base metals. If thena-small quantity of water is added to the ore-body-in a leaching vessel,

some of the chlorid salts are dissolved, and

in this solution the chlorids of gold andsilQ ver are readily soluble.This operation facilitates the subsequent leaching process with ammonia,because a part of the soluble metal salts is removed from the ore-body.Besides this, the washing with water prior to the introduction of theammonia solvent reduces the vehement reaction which takes place whenore, raw or roasted, with or without salt, moistened or not, isgradually fed into a closed leaching vessel containing the ammoniasolvent. Such vehement reaction will create heat and the ammonia isdriven out,

thus prod ucinga great pressure. As a result of all this, the liquidbecomes free of the volatile ammonia, and therefore f u rtherdissolution ceases, and on the other hand cupric or metal oxids areprecipitated in the ore-body according to the following equation, viz:

These different phenomena combined result in a low extraction an theprecipitation of the metal oxide in the ore-body entails loss. Now Iovercome all these chemical and physical difficulties by chargingv firstthe ore, giving a wash with water, and then I introduce the ammonia-stock solution into the leaching vessel. The ammonia herebycombines with the metals, forming ammoniated cupric or There being avery small quantity of volatile ammonia present only little ammonia canbe driven out by the heat; produced by the reaction and no seriouspressure will occur, and such heat as is produced is taken up by theincoming stock solution, only slightly raising its temperature. Forthese several reasons my new method of adding the solvent to theore-body is far superior to the old method of adding the ore to thesolvent. This shows that laboratory reactions and laboratory processesare in many cases not reliable for hydrometallurgical purposes,

. Y t t 'if converted into another salt.

The solution obtained by the water-wash of the ore in the leachingvessel contains the precious metals andis passed into what I call thegold-tank. This water-washing is carried on with a small quantity ofwater, and

then I leach with ammonia-stock solution and with the liquids comingfrom the wash-water and'boiled-out storage-tanks, about which liquids Iwill give'a' fullexplanation later on. Hereby the balance of the solublemetal salts and of chlorid of silver is dissolved. The formed ammoniatedcopper orinetal solution may now be passed into the gold-tank and theninto a settler or directly into a settler.

In the latter case ammonia-stock solution is passed into said gold-tankand from there into a settler. In either case gold and iron dissolved inthe chlorid solution are precipitated. The metal salts, however, withthe chlorid of silver, are dissolved as ammoniated copper or metalcompounds. They pass through a filter into asettler and unite with thepreviously-obtained ammoniated copper or metal solutionfrom the leachingvessel. Of course if separate treatment is desired the two extractionsare passed into two separate settlers. After washing the precipitates inthe gold-tank they may be melted and will give metallic gold. The goldprecipitated with ammonia forms an explosive, and the reducing ormelting can only safely be done Also silver will hereby be precipitatedif cuprous chlorid or sulfate is in the solution, and then I prefer todissolve the precipitated gold and silver compounds after washing in -asolution of cyanid of potassium or Na,S O solution, as they are readilysoluble in such solutions, and recover them in the usual way.

Instead of precipitating the gold in the goldtank, as aforesaid,the goldand silver can be recovered by galvanic action or any otherapproved'method. As regards the chlorid of silver, and also if some goldis yet retained in solution by the ammonia, it is recovered as cement,silver, and gold in the settler by galvanic action. It is desirablethatathorough chlorination or chloridizing should have taken place";otherwise the greater part of the gold remains in the ore-body, butfortunately in such a condition that it can easily be recovered by acyanid solution after the ore has been treated withammonia. I usuallykeep the strength of theammoniated metal solution for boiling-outpurposes at two to four pounds of metal per cubic foot. The ore 53tares-sta with the ammonia-stoc solution. and the said liquidsis drainedand iashed, 'vin as first product an extraction :ofgradually-diminishing strength.- This I pass into the solution-settler.vi thej'washing and draining, finally with wa- I continue tor, until allmetal is removed, which is indicatedlby absence of .color in thewash-wator, and I'pass this second product of washzo'ling into awash-water settler, from where, after settli ng,I pass the wash-waterinto the wash-water storage-tank. From this tank I draw when making thefirst product of extraction of thenext chargein the'lea'ching vessel.After settling the solution in the settler, if clear, is passed directlyinto the still. If turbid, it first passes through a-quartz-filter. Wehave now in the still and ready for precipitation a solution of copper,nickel, and

zinc. I pass into the still some alkali, preferably caustic soda,and-adjust the quantity to the quantity of the three metals in thestill. Supposing the extraction of one ton of ore gave a solution of onehundred pounds of copper,

fifty pounds of. nickel, and one hundred pounds of zinc, then I chargethree hundred the cnpric oxid by boiling the solution with steam. Thisprecipitation is retarded, par ticularly at the last stage of theprocess, by the presence of basic cupricsammonium com- .pounds in thesolution. This compound is 4 more especially formed in large quantitiesit hot air be employed in the boiling-out process. extent by passinginto the still condensed ammonia vapors. coming from the condensingsystem, as will be seen in the drawing of the applicationforthe'apparatus filed by me; but if large quantities of these objectionable compounds'are present I obtain an immediate result by forcing afew pounds of alkali solution from the alkali-tank at the.

last stage of the boiling-out process into the still,- a s above stated;The separation of the cupric oxid from the ammonia is yery rapidand'c'omplete. The reaction, it chloride are treated, is as follows,viz:

This improved process is used if the ore is treated only for copper, as-I have stated before. The boiled-out solution is, after cooling, usedover and over again for extraction purposes, as aforesaid, untilsaturated with salts. Then it is charged into a lime-still,

where the non-volatileammonia compounds are separated in the usualmanner, forming lime-salts and free ammonia, which latter I overcomethedifficulty to a certain is recovered in a condensing. system, asdescribed in the applications for the apparatus. From the foregoing itfollows that only such water as is discharged together with same withsteam. The copper precipitates as cupric oxid and the nickel as hydratednickel monoxid'; but'the zinc, if small quantities are present, isobtained in solution as soda zincate. If large quantities are present,Iprefer 'to discharge the boiled-out solution into a pan and add acaustic-soda solution to the precipitates of the oxids and boil intosteam, whereby all of. the zinc. is dissolved as soda zincate and acomplete separation takes place if agitated by steam. The clear solutionI discharge in the same pan, as aforesaid, and also the wash-water,which dilutes the zinc solution, and hydrated zinc oxid (zinc white, ifdry) is precipitated, which is shoveled out, dried, and sold, or it isreduced to metallic zinc in a furnace By boiling the metal solution inthe still all of the ammonia is liberated very rapidly and recovered inthe condensing system and collected in the ammonia-stock-solution tankas high-grade aquaammonia. I'rnay-use 'for the absorption of the ammoniavapors boiled-out solution or water. The ammonia thus recovered is used-bythe next batch of ore for dissolving purtests on a large scale. Afterthe copper and.

nickel oxids have settledin the still and the sodazincate and wash-waterare discharged into the pan I change to the copper and nickel oxids inthe still boiled-out solution or water- I containing ammonium compounds,such as N H Gl(NH SO,. I have discovered that cupric oxid is insolublein warm ammonium c0mpounds, whereas hydrated nickel oxid is readily.soluble. still ammonium compounds solutions and heat slightly, agitatingat the same time with steam, whereby a most perfect and completeseparation of the two oxids takes place, the

nickel oxid entering into solution and the I therefore charge into the asystem. The process of precipitating is rendered complete by adding somecaustic'soda,

After the separated copper and nickel oxids are settled in theirrespective stills the su-- and over again in theleaching vessel for,

leaching new batches of ore or for manufacturing aqua-ammonia in theammonia-stocksolution tank. After rotating this boiled-out solution forsome time it becomes saturated with salts. I discharge it then into thelimestill and recover all the ammonia by boiling it with lime andagitating it by an agitator. This ammonia is also recovered in thecondensing system; but a separate system may be employed, especially byplants with a large capacity. The oxids are discharged into troughs,shoveled to drainers, and dried in an oven. The o'xids are sold as suchorreduced to metals in separate furnaces. solution in the pan where thezinc-white was precipitated and recovered contains some caustic soda,salts of chlorid, and sulfate of sodium. The two latter crystallize outby evaporating some ofthe solution, and these salts are shoveled out,drained and dried, and used for charging the raw ore in'theroasting-furnace, where it performs a most perfect" and completechlorinating roast. The remaining caustic-soda liquor is used over againin the distillation of a next batch of ammoniated-metal solution comingfrom the settler and leaching vessel.

This leaching process is very cheap and economic and allows thesuccessful treatment of the most complex and refractory ores andtailings. I The only heavy expense is for the purchase of caustic soda,the quotation prifie of which is one and eight one-hundredths cents perpound, and the average consumption for such ore as described above isnot more than two hundred pounds per ton, wh ich would amount to threedollars and sixty cents per ton. Adding cost of mining, fuel-,l'abor,he, the whole expense per ton of ore ,is'not more than eight dollars,whereby one hundred pounds of copper, one hundred pounds of zinc, andfifty pounds of nickel are produced with a total value of forty-four.dollars,- besides-recovering the precious metals ofv the ore asby-products and at a nominal cost.

The plant to be used for carrying out this process is cheap and simple.

. This process is the best substitute for any known process of treatingall classes of ores.

The condensing system allows the manufacture of aqua-ammonia of allgrades up to 26 Baum.

The quantity usedfor each batch'of' ore is calculated according to theanalysis and the atomic weight of the metals to be treated and I preferto employ an ammonia about 18 Baum for dissolving purposes.

covering gold or gold and silver by chemical and galvanic action; third,dissolving with NH forming OuCl ZnCl NiC] (NH,)m; fourth, precipitatingCuO and Ni(l-IO) with caustic soda and heat, recovering (NHQw and alsoZnO;

If sulfates are formed, the Cl is simply substituted by S0 If Ag and Auare present and desired to be recovered, a chlorinating roast isnecessary. It is obvious that if only one, two, or more of said metalsaretpresent in the ore the process remains the same, only the operationis simplified, confining it to the particular metal or metals.

In the settlers slimes accumulate, and after some time (one month or so)I discharge the slimes into the slime-washer, wherein I wash with coldwater first and then with warm water', agitating the mass with steam,the escaping ammonia being hereby removed androcovere'd in thecondensing system. I The washwater as long as any color is'noti'ceableis passed into the wash-water-storage tank to be used over and overagain in the process in the same manner as the wash-water from thewash-water settler. The slimesif they do .not contain any preciousmetals are discharged tot-he yard; but if they contain precious metals.they may be now recovered by any approved process.

It is known that gold'and silver oresif treated successfully withmercury ora cyanidof-potassium solution. I have found that thedifficulty can be covercome by first removing the base metals by ammoniawith or without previous moistening and then either washing the products'of extraction or recovering them in the manner described above. Afterthis treatment the gold andsilver can be successfully extracted withmercury or cyanidof-potassium solution. I

It is obvious that ores-or tailings containing a high percentage ofsoluble metal salts in hot boiled-out solution or hot water produced inthe condensing system can'be successfully extracted in tanks open on topwith such hot too they contain some base metals cannot be water, and theobtained. metal solution can now be charged directly into the still withammonia and compounds thereof or with ammonia and-an"a'lk ali. If thenboiled, the

metal'acids willbe precipitated, containing some slimes and ferric acid.After discharging and drying briquets can be formed, which can bereduced in a furnace to metallic copper or metals. The escaping ammoniafrom the still of course is recovered in the same manner as previouslydescribed.

It is obvious that raw ores and tailings containing soluble metal saltsin my solvents yield to the same treatment as the roasted ores,andtherefore come properly within the subject-matter of my invention.

Having described my invention, I claim as new an'ddesire to secure byLetters Patent vag na ing therefrom the metal of metals separately andthe ammonia, substantially as described. 2. The process of treatingchlorinated ores and tailings, which consists'in washing with water,leaching with ammonia, or ammonium sulfate, chlorid or nitrate, addingwater-or wash-water, or boiled-out solution obtained by the operationofthe process, and recover- .ing therefrom themetal or metals separatelyand the ammonia, substantiallyas described.

3. The process of treating roasted ores and i tailings, which consistsin mixing the same with an acidulated' solution,- washing withwater-,leaching with ammonia, or ammonium sulfate,"chlorid or nitrate,adding water or wash-water, or boiled-out solution obtained by theoperation of the process,- and recovering therefrom the metal or metalsseparately. and the ammonia, substantially as described. 4. The processof treating chlorinated ores and tailings, which consists in mixing thesame with an acidulated solution, washing with water, leaching withammonia or ammonium sulfate, chlorid or nitrate, adding water orwash-water, or boiled-out solution obtained bythe operation of theprocess, and recovering therefrom the metal or metals separately-and theammonia, substantially as described.

5. The-process of treating ores or tailings,

' containing 'gold, silver, copper, nickel and zinc, which consists inwashing with water, leaching with ammonia and compounds thereof, andthen recovering the precious metals by any approved method,substantially as described. l

6. The process of treating ores or tailings, containing gold, silver,copper, nickel and zinc,which consists in moistening with acidulatedsolution, washing withwater, leachingwith ammonia and compounds thereofand then recovering the precious metals by any approvedmethod,substantially as described.

7. The process of treating chloridized-ores and chloridized tailings,containing gold, silver, copper, nickel and zinc, which consists inwashing with water, leaching with am monia or ammonium sulfate, chloridor. nitrate,

adding water or wash-water, or'boiled-o'nt so lution obtained by theoperation of the process, precipitating the'gold from the wash solutionby'adding ammonia-,;recovering"it as metallic gold, and recovering theother metals and ammonia separately, substantially as described.

' 8. The processof treating ores and tailings,

containing gold, silver, copper, nickel and zinc, which consists inWashing with water,

leaching with ammonia, or ammonium sulfate, chlorid or nitrate, addingwater or washwater, 'orboilcd-out solution obtained by the operation.ofthe process, precipitating the gold from the wash solution by addingam Q monia, recovering it as metallic gold and precipitating from theformed am monia metal solution the silver by galvanic action, andrecovering the other metals and ammonia separately, substantially asdescribed.

9. Theprocess of treating ores and tailings containing gold, silver,copper, nickel and zinc, which consists ih washing with water, leachingwith ammonia and com pounds thereof, adding water or wash-water from aprevious washing or boiled-out solution, precipi- 8o tating the goldfrom the wash solution by adding ammonia, precipit ting from theammo'nia-metal solution the silver by galvanic, action, precipitatingthe base metals by boiling and the addition of caustic soda or alkalies,discharging the boiled-out solution and adding caustic-soda solution tothe alkalies, thereby dissolving the zinc as soda zincite, dischargingthe solution into a receptacle and diluting said solution, wherebyhydrated zinc 9o oxid Zn(0H) is precipitated, evaporating some of thesolution so as to recover sodium chlorid, sulfate crystals and causticliquor,

.and recovering separately the two remaining metals and the ammonia,substantially asde- 5 scribed.

10. The process of treating-ores and tailings containing gold, silver,copper, nickel and zinc, which consists in washing with water, leachingwith ammonia,- or ammonium sulxoo fate, chlorid or nitrate, addingwater, or washwater from a previous washing or-boiled-out solution,precipitating gold and silver from the solution by means of galvanicaction, precipitating the base metals as oxide by adding caustic soda orits equivalent and boiling the solution, discharging the boiled-out,

solution, adding caustic soda to the precipie tated oxids, therebydissolving zinc as sodium zincite, removing this solution of sodium nozincite and diluting the same, thereby pre-. cipitating zinc hydrate,addinga solution of ammonium compounds capable of dissolving i nickeloxid, to the oxids from which the so- .dium zincite was removed, therebydissolve ing the nickel osid, and leaving'the copper oxid undissolved,withdrawing the dissolved nickel, adding caustic soda thereto, andboiling, thereby precipitating nickel hydrateand liberating ammoniuin,which is recovered, :20

substantially as described.

11. The process of treating acid ores and tailings,'containing gold,silver,copper, nickel and zinc, which consists in washingwith wa-'ter,leaching' with ammonia,or withammonium z 2 5 .perammoniumcompounds, and recovering .all of the copper separately from theammonia, substantially as described.

12. The process of treating acid ores or tailings,containing gold,silver, copper,nickel and zinc, which consists in washing with water,leaching with ammonia, or with ammoboiled-out solution, precipitatingthe copper as cupric cxid by boiling and passing condensed ammoniavapors into the metal solution to break up the formed basic-copperanimonium compounds, and recovering allot the copperseparately from theammonia, substan: tially as described.

13. The process of treating ores or tailings,

which consistsiu washing with water, leaching .with ammonia, or withammonium sulfate,- chlorid or nitrate, adding water or Washwater, orboiled-out solution obtained by the operation of the process andcharging the solvents to the ore, whereby no precipitation in theore-body by the heat and. pressure results, thus assuring a highextraction.

14. The process of treating ores or tailings, which consists in washingwith water, leaching with ammonia, or with ammonium sul fate, chlorid ornitrate, adding water or washwater, orboiled-out solution obtained bythe operation of the process, washing first with water and charging thenthe solvent of ammonia and compounds thereof to the ore, whereby-noprecipitation in the ore-body by heat and pressure results, thusassuring a high extraction.

15. The process of treating ores or tailings, which consists in washingwith water, leaching with ammonia, or with ammonium sulfate,'chlorid ornitrate, adding water or wash- -water from a previous washing orboiled-out nia for leaching, substantially as described.

16. The process of treating acid ores or tailings', containing gold,silver, copper, nickel and zinc, having reference to sulfate ores,

which consists of dissolving the metals in'hot.

the'ammonia combined with them, substanmany as described.

.17: The process of treating acid ores and tailin gs, containing gold,silver,copper,nicke l and zinc, having reference to sulfate'ores,

which consists of dissolving the metals in hot boiled-out solution orhot water, charging to the solution am monia'and adding at the laststage of the boiling-out process some caustic soda into the metalsolution to break up the copper or basic-metal ammonium compound,

then recovering all the copper or metal oxids and all the ammoniacombined with them substantially as described.

18. The process herein described for extracting gold, silver, copper,nickel and zinc from substances containing the same, which consists insubjecting said substances to the action of an acid, washing with waterthe substance thus treated, thereby forming solutions containingcompounds of gold and base metals, and then subjecting said solutions tothe action of ammonia for the purpose of prccipitating'the gold andrecovering the base metals from the solution separately and also theammonia, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

HENRY HIRsouINGf Witnesses:

FRANK TEICHMANN, 7 CHARLES W. HENDE-L.

